The visual "mobiles" attached to infant cribs are devices designed to provide the infant with visual stimulation. There are no devices currently on the market that provide infants with complex and interesting auditory stimulation. Yet, studies by this research team show that very young infants have a keen sense of hearing and are capable of discriminating fine differences in complex sounds such as speech. More importantly, our work suggests that infants like listening to speech, particularly when it conforms to the kind of speech that is addressed to them by caretakers. The particular kind of speech has many special properties, and has been given the name "Motherese." Our laboratory research indicates that infants prefer to listen to Motherese over the kind of speech that is addressed to adults. Moreover, the work shows that the main feature attracting infant attention towards Motherese is its unique acoustic characteristics, indluding an increase in pitch, exaggerated pitch contours, and a slower tempo. This Phase-I research project proposes to examine the feasibility of creating an "Auditory Mobile" for infants--a device that presents Motherese and other complex signals that mimic its salient acoustic characteristics to infants. The special features of this device include the fact that it is programmable and activated by the infant's vocalizations. The proposal requests support for research that would further specify the parameters of auditory signals that should be contained in an Auditory Mobile and begin work on the technical problems of speech synthesis and recognition required by the device.